Need some help please 1995 Jimmy 4wd wont engage


rollnthunder_76
03-17-2006, 05:40 AM
I have replaced the encoder motor on the transfer case along with the vacum switch.I unpluged the vacum lines at the t case and started the vehicle i have vacum to one of the lines.But when i push the button on the dash all i get is a blinking light for about 10 seconds then the 2hi lights back up solid.You can also hear the module in the lower part of the dash click once when you first push the button and then again when it stops blinking and goes back to 2hi.Any one have any ideas.

rlith
03-18-2006, 08:42 AM
I have replaced the encoder motor on the transfer case along with the vacum switch.I unpluged the vacum lines at the t case and started the vehicle i have vacum to one of the lines.But when i push the button on the dash all i get is a blinking light for about 10 seconds then the 2hi lights back up solid.You can also hear the module in the lower part of the dash click once when you first push the button and then again when it stops blinking and goes back to 2hi.Any one have any ideas.

More than likely it's the vac actuator under the battery tray...



1st Check vac actuator under battery tray for tears, or leaks, and that the vac hose is connected. Replace if found

2nd Check vac hose leading from vac actuator to vac switch on transfer case for cracks and dry rot. Replace if found.

3rd Check remaining 2 hoses from vac switch on transfer case for dryrot or cracks Replace if found.

If all of the above are fine, disconnect your negative battery cable for 1/2 hour then reconnect it. If your 4x4 works after that you probably have a failing TCCM (Transfer case control module)

If that doesn't solve it, it's most likely the encoder motor

rollnthunder_76
03-19-2006, 07:58 PM
Now if that vacum module under the battery is bad or leaking will that keep the tcase from engaging or will it just keep the front axle from engaging?I was wondering how it all worked together.I thought well maybe the front axle engages first then that tells the tcase its ok to engage.But then i have been reading where people complain the tcase is engaged but the front wheels dont turn.I will have to do some more work and check things out.Thanks for the help and keep it coming...lol

rlith
03-19-2006, 08:13 PM
Now if that vacum module under the battery is bad or leaking will that keep the tcase from engaging or will it just keep the front axle from engaging?I was wondering how it all worked together.I thought well maybe the front axle engages first then that tells the tcase its ok to engage.But then i have been reading where people complain the tcase is engaged but the front wheels dont turn.I will have to do some more work and check things out.Thanks for the help and keep it coming...lol

If the vac actuator under the battery isn't getting vacume, the front will not engage. The transfer case motor engages, setting off the vac switch on the tcase, causing vacum to the actuator under the battery, causing the front to lock.

rollnthunder_76
03-20-2006, 04:32 AM
Well then i would have to think its something to do with vacum or that tccm because the tcase is not engaging at all.I guess i could jack it up and have someone hit the button and see if the front axle trys to engage.Is there a way to check the shift motor on the tcase?I just replaced it and i pulled the positive cable for a few minutes.Is the tccm the part in the dash?

rlith
03-20-2006, 06:42 AM
Well then i would have to think its something to do with vacum or that tccm because the tcase is not engaging at all.I guess i could jack it up and have someone hit the button and see if the front axle trys to engage.Is there a way to check the shift motor on the tcase?I just replaced it and i pulled the positive cable for a few minutes.Is the tccm the part in the dash?

Just follow the steps as outline, it will tell you the probelem

rollnthunder_76
03-21-2006, 07:56 PM
I dont have any vacum to the actuator under the battery.I traced it back and it looks ok.

rlith
03-21-2006, 09:13 PM
I dont have any vacum to the actuator under the battery.I traced it back and it looks ok.

You then have to trace and change any broken hoses, if the hoses are all right it's the vac switch on top of the transfer case. The vac switch gets it's vac from the engine.

rollnthunder_76
03-22-2006, 05:22 AM
I have already replaced the vacum switch.I did find one hose not hooked to anything it was zip tied to the transmission filler tube and i couldnt find any other hose in that are that it would hook to.I guess i will get alot vacum line and start replacing.I know from the motor down to the switch i got vacum.

rollnthunder_76
03-22-2006, 10:53 PM
Ok heres what i got.I took the vacum switch out and started the vehicle and then i pushed the vacum switch in with my finger and i had vacum to the front actuator and it engaged the front axle.But I dont have power to the encoder motor.I took a volt meter and probed the plug at the encoder motor and i got nothing when the button is pressed.I also just swapped out the tccm and got the same thing.I have checked all the fuses and i cant figure out why i dont have power down to the encoder motor.Is there anything else relays or anything maybe a switch?

I think i understand how this system works the button is pressed gives power to the encoder motor which then switches the transfer case to 4hi or lo and that pushes something up agianst the vacum switch which then sends vacum to the front actuator to engage the front axle.So this means if the encoder motor doesnt engage the Tcase you wont ever have vacum to the front actuator.

95xjsport
04-02-2006, 09:55 PM
mine does the same thing, now how does the transfer case actually shift??

rlith
04-03-2006, 07:27 PM
mine does the same thing, now how does the transfer case actually shift??

An electronic signal kicks the encoder motor

95xjsport
04-04-2006, 09:54 PM
where on the transfer case would this vaccume switch be?

rlith
04-05-2006, 07:25 AM
where on the transfer case would this vaccume switch be?

The top.. You will see 3 hoses going into it... Uses a 7/8 boc wrench to remove.

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